| Dubuque to Smolyan | 5,373.58 mi (8,647.94 km) |
| Dubuque to Sofia | 5,269.30 mi (8,480.12 km) |
| Dubuque to Sopot | 5,321.45 mi (8,564.04 km) |
| Dubuque to Sozopol | 5,434.36 mi (8,745.76 km) |
| Dubuque to Sredets | 5,420.89 mi (8,724.08 km) |
| Dubuque to Stamboliyski | 5,339.95 mi (8,593.82 km) |
| Dubuque to Stara Zagora | 5,363.57 mi (8,631.83 km) |
| Dubuque to Svilengrad | 5,416.60 mi (8,717.18 km) |
| Dubuque to Svishtov | 5,293.23 mi (8,518.63 km) |
| Dubuque to Targovishte | 5,353.73 mi (8,616.00 km) |
| Dubuque to Teteven | 5,291.23 mi (8,515.42 km) |
| Dubuque to Troyan | 5,308.53 mi (8,543.25 km) |
| Dubuque to Tryavna | 5,336.37 mi (8,588.05 km) |
| Dubuque to Tutrakan | 5,313.91 mi (8,551.91 km) |
| Dubuque to Varna | 5,400.16 mi (8,690.73 km) |
